Described below is a method of acknowledging data in a communications system.
General Packet Radio Service (GPRS) data is transmitted in radio link control (RLC)/medium access control (MAC) blocks. These higher layer data blocks are coded and transmitted in lower layer protocol blocks, known as radio blocks. Depending on the coding scheme, there are typically one or two RLC/MAC blocks per radio block. A radio block typically includes one header and one or two RLC/MAC blocks. Decoding of the header is a pre-requisite for decoding the RLC/MAC block(s).
In the 3rd Generation Partnership Project (3GPP) General Packet Radio Service (GPRS)/Enhanced Data for global system for mobile communication (GSM) Evolution (EDGE) Radio Access Network (GERAN) there is work in progress to introduce ‘Fast Ack/Nack Reports’ (FANR). Acknowledgement of received data has been known by a specific message, such as Packet Downlink Ack/Nack, which contains acknowledgement data and possibly other control data, but does not contain any user data.
The idea of FANR is to include a small amount of acknowledgement data together with user data within the same radio block. The benefit of this is that these blocks can be sent more frequently, allowing the peer device to re-send, more quickly, blocks which were not received correctly. If existing messages were sent with a higher frequency, there would be a significant decrease in the capacity to send user data, and there would be significant redundancy in the acknowledgement messages.